sndfile-regtest: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/sndfile-regtest - from package: libsndfile

You may install the required package with command yum install {package}

Error in other languages:
sndfile-regtest: bevel nie gevind nie
sndfile-regtest: comandă negăsită
sndfile-regtest: comando não encontrado
sndfile-regtest: commande introuvable
sndfile-regtest: command not found
sndfile-regtest: käsku ei ole
sndfile-regtest: không tìm thấy lệnh
sndfile-regtest: komanda nerasta
sndfile-regtest: Kommando nicht gefunden.
sndfile-regtest: kommandot finns inte
sndfile-regtest: komut yok
sndfile-regtest: nie znaleziono polecenia
sndfile-regtest: níor aimsíodh an t-ordú
sndfile-regtest: no se encontró la orden
sndfile-regtest: no s'ha trobat l'ordre
sndfile-regtest: opdracht niet gevonden
sndfile-regtest: parancs nem található
sndfile-regtest: perintah tidak ditemukan
sndfile-regtest: príkaz nenájdený
sndfile-regtest: příkaz nenalezen
sndfile-regtest: команда не найдена
sndfile-regtest: командата не е открита
sndfile-regtest: 命令找不到
sndfile-regtest: コマンドが見つかりません